Electrical protective device.



eras PATENT. curios.

BENJAMIN SMITH, OF TURTLE CREEK, PENNSYLVAEIA, ASS IIIGNOR TQ WESTING I HOUSEELECTRIC AND MANUFACTURING GOMPANY, A CORZPOBATIONOF EENESYL- VANIA.

Application filed December 29, 1914.. Serial No. 879391 To all whom it may concern: Be it known that I, BENJAMIN H. SMITH, a citizen of the United States, and aresident of Turtle Creek, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Protective Devices, of which the following is a specification.

My-invention relates to electrical protec- L .tiye devices and particularly to relay mechanisms that are employed for tripping c1r-' cuit ,interrupters or other similar devices Qupon the oceurrenee'o'f predetermined circult conditions.

My invention has for its object to provide a device of the character above indicated that will operate correctly upon any value of overload.

My copending application, Serial #850,331, filed July 11, 1914, discloses a a relay system that comprises a time-element relay which is adapted to control an aurailiary winding on a tripping electromagnet for the purpose of permitting the electromagnet to operate under predetermined con ditions. With a device of th1s type, a circuit interrupter may be tripped by current [derived from a circuit in connection with.

'which the circuit interrupter is employed Without subjecting the contact members of the relay to any injurious arcing or welding. However, when a device of this type is employed to interrupt very large currents, the tripping electromagnet will frequently operate irrespective of the auxiliary winding that is-controlled by the relay; 3

sive overloads and the other part, that actu-' 'ates the latch, is operated in response to the'control or auxiliary winding of the relay, thus providing a device that is operative for all values of current.

Figure 1 ol": the accompanying drawings diagrammatimllyillustrates a part of a system embodying myinvention, and Fig.

2 is a detail illustration of a tripping electroinagnet embodying my invention. An alternating currentcircuit 1. 1 s provided with an interrupter 2 for opening it. under predetermined conditions. 7 In order to trip .the.circuit-interrupter 2, I pride Specification of Letters Patent.

"rinnornronr. rno'rncrrvn FJEVIGE.

Patented Nov. 14, 1916.

a relay system 3 that derives itsenergyirom the circuit 1 through a current transformer Al and a voltage transformer 5. The relay magnet 7. The secondary winding 8 of the transformer 5 is connected to the windings 9 and 10 of the'relay 6, and the secondary winding 11 of the transformer dis connected in series relation to the winding 12 of the relay 6 and the windings 13 and 14 of the electromagnet 7. The relay 6 is provided with an armature 15 that is mounted on a shaft 16 which is provided with a contact arm 1'4". The contact arm 17 cooperates with a. contact member 26 for the purpose of controlling the circuit of auxiliary or controlling winding 18 of the electromagnet 7 The electromagnet '5 comprises a stationary magnetizable core member 19 in the form of a hollow rectangle having a polepiece 29' extending inwardly and downwardly from the upper cross-piece thereof and having a gap in the lower crosspiece through which projects a movable core member 21 that is adapted for longitudinal vertical movement. A substantially iii-shaped portion 22 is mounted with its longer legs terminating adjacent to the lower end of the core member 19. The movable core member .21 normally rests upon the middle leg or pole'piece of the core part and, together with the said middle Inorder to cause the tripping electro-fl leg or pole piece, is surrounded by the windings and The movable core member rises two parts 23 and 24 that are relatively movable with respect to each other and are operatively connected together by a spring 25. The lower part 24 is connected to ancperating rod- 27 and the upper part 23 is loosely disposed about the rod 27, substantially as shown in Fig. 2 of the drawing.

As liereinbefore stated, the windings 13 and lare supplied with current from the secondary winding 11 of the transformer a and are preferably connected in series with the winding 12 of the relay 6, although they may be connected in any other suitable re lation with respect thereto.

to be closed-circuitd by the engagement of contact members I? and 26 of the relay The winding -18 is normally open-c reuited but s adapted 6, under predetermined circuit conditions, such, for instance, as upon the occurrence of an overloador a reversal of the direction of flow of energy in the circuit 1 Under normal circuit conditions, th current in the winding 12 of the relay (Yrs insufiicient to cause the switch 1'726. to close, and consequently, the winding 18 remains open-circuited and is not affected. Howeventhe windings 13 and let are continuously energized so long as the circuit interrupter 2 remains closed, but, being located upon opposite sides of the lower end cross-piece of the core member 19, and being also provided with separate magnetic circuits, they exert opposing forces upon the core memher 21. The magnetic circuit of the wind ing 14 being substantially closed, under normal conditions, the movable core member 21 remains stationary in the position shown. Also, since the magnetic circuit of the winding 14 is normally closed whereas, a considerable air gap exists in the magnetic circuit of the winding 13 at the upper end of the movable core member 21, it is obvious that-the winding 14 may, and preferably does, have a smaller number of convolutions than the winding 13.

lVhen an overload or other abnormal condition occurs upon the circuit 1, an increased current is induced in the w' iding 11 of the transformer L which is sutlicient to cause the relay 6 to close the switch 17-26, the closing of which may be delayed or not, as desired. When the switch 1726 is closed, the'winding 18 is closed-circuited and an electromotive force is induced by it in the winding 14:, thereby decreasing the magnetizing effect of the winding 14 because of the counter flux produced by the winding 18.

'lVhen the magnetizing effect of the winding on the circuit 1. sutlicient current would traverse the winding 13 to cause the movable core member 21 to operate irrespective of the operation of the relay-6. In order to avoid this condition. the movable core member 21 is composed of the two relatively movable parts 23 and 2-1 that operate substantially as follows: When the excessive overload occurs, the part 23 is moved upwardly by the force of the current traversing the winding 13, and the part 24 s re tained in its initial position by the force. in-

cident to the current tra ersing the winding 14:. After the relay 6 has operated to close the switch 17-26, the winding 18 is closedcircuited, thus wealenin the effect of the winding 14.- and permitting the spring to draw the part 24 upwardly. Since the part E i-is connected to the rod 27, the upward movement of the same trips the circuit breaker 2, substantially as hereinbefore set forth. 1

lVhile I have shown and described my invention in a preferred form. it may, obviously, be variously modified within the scope of the appendetl claims.

I claim as my invention:

1. An electromagnetic device comprising a stationary core member. a movable core member having two magnetizable portions. means. for resiliently connecting the two poi tions together, two main windings tor the movable core member adapted to move the two portions of the core member in opp-osite directions and an auxiliary windingtor neutralizing the effect of one of the main windings under predetermined comlitions. 2. An electromagnet comprising a stationary core member. a movable cor-e member having two relatively movable magnetg izable parts, a resilient member for operatively connecting the two parts together,

two windings adapted to move the two parts of the core member in opposite directions, and means for neutralizing the etl'eet of one of the said windings under predetermined conditions. I

3. In a relay system, the con'ibination with a relay, of an electromagnet comprising a stationary core member, a two-part movable core member, a spring for operativcly con necting the two parts together, two wind= ings adapted to produce opposing pulls upon the two parts of the inovablecore member and a third winding that is controlled by the said relay for neutralizing the effect of one of the said windings under predetermined conditions.

14. An electromagnetic device comprising a stationary core member, a two-part movable core member, means for resiliently connecting the two parts of the movable core member together, means tending to move the two parts of the core member in opposite directions and means for so neutralizing the said means that the two parts are permitted to move in the same direction under predetermined conditions.

An electromagnetic device comprising winding'ior decreasing the flux in one of the 7 said magnetic paths to permit both parts of the movable core member to-move inone direction.

6. An electromagnetcomprising a. mov- I able core member navingtw-o relatively movabie magnetizable parts resiliently connected together, a normally energized wind- 'ing tending to move one part of the movpredetermined conditions. .7. An electromagnet comprising two movable jcoje members, means for resiliently connectin the sametogether, a. normally of the said movable core members and a second winding for preventing the actua tion of the other movable core member and a third Winding'for neutralizing the'eiiect of the' said'second vindin under redetermined Loonditions.

An electromagnet comprising two movable core parts, a tripping rod operatively connected to one of the said [0026 parts the other core part beingloosely disposed about the said rod, a spring for operatively c0nnecting the two core parts together, a wind ing tending to actuate the loosely disposed cbre part, and a second winding adapted to prevent the actuation of the core part that is attached to the said rod except under predetermined conditions.

9. An electromagnet comprising two movable cor v members, a spring for operatively connecting the core members togethene rod operatively connected to one of the core members, means tending to move the said core members in opposite directions, and means'ior permitting the said coremember that is operatively connected to the rod to movein the-same direction as the other core member under predetermined 7 conditions.

10. An electromagnetic device --comprising a stationary core member, two movable magnetizable core members therefor, a spring operatively connected between the movable core members, means tending to move the core members in opposite directions and means for causing the movable core mem- ,bers to move in one direction-under prede tel-mined conditions;

11. An electromagnet comprising two movable core members, a spring operatively connected between the movable core memoers, a winding tend ng to move the core members in opposite directions and means for causing the movable core members to move in one direction under predetermined conditions.

12. The combination with an electric circuit and a relay having an actuating windtreating the movable core member that the energized winding tending to actuate one two parts are permittedto move in the same direction.

13. The combination-with an electric circuit and a'relay having an actuating winding, of an electromagnet comprin'ng a stationary core member, a two-part movable core member, means for resiliently connecting the two parts of the movable core member together, means connected in'series with the relay winding tending to move the two parts of the core member in opposite directions, and a normally open-circuited winding adapted to be closed-circuited by. the relay for neutralizing the said means for ay winding, tending to move the two actuating the movable core member under predetermined conditions.

l hThe combination with an electric circuit and a relay having an actuating winding, of an electromagnet comprising a stationary core member, a, two-part -movable core member, means forresiliently connecting the two parts of themovable core member together, a main winding connected in series with the .relay winding for tending to move the two parts of the core member in opposite directions, and a normally opencircuited winding adapted to .be closed-air cuited by the relay for neutralizingthe effect ofthe main winding on one part of the movable coi'e memberunder predetermined conditions.

In testimony whereof, I have hereunto subscribed my name this 22nd da'yof Dec,,

' snnJAM n. SMITH.

Witnesses Geo. M. Lrrrin, B. B. HINES. 

